TOKYO, Japan - Princess Aiko along with her father and mother, Crown Prince Naruhito and Crown Princess Masako, wave as they leave the Imperial Palace in Tokyo by car on Dec. 1 after seeing her grandparents -- Emperor Akihito and Empress Michiko -- to report on her second birthday. (Kyodo)

TOKYO, Japan - Princess Aiko, the daughter of Crown Prince Naruhito and Crown Princess Masako, turns 2 on Dec. 1. The photo was taken by the Imperial Household Agency on Nov. 18 at their residence in Tokyo. (Kyodo)

TOKYO (AFP) - Princess Masako, the wife of Japan&#39;s Crown Prince Naruhito, was hospitalised with the painful virus shingles, forcing her to skip events marking her 40th birthday five days from now.

She was admitted Thursday to the Imperial Household Agency Hospital, located on the premise of the Imperial Palace, and was to receive treatment, including intravenous feeding, for several days, an agency official said.

The imperial household hospital said on Wednesday that the princess had developed painful rashes on the back of her head and under her chin the day before.

"There has been no change in her condition but we wanted to provide most sufficient treatment," the official said.

Shingles, or herpes zoster, is an acute infection caused by the same virus which causes chickenpox.

Japanese Princess Aiko &reg;, in the arms of her mother Crown Princess Masako, who was hospitalised with the painful virus shingles, forcing her to skip events marking her 40th birthday five days from now.(AFP/File/Yoshikazu Tsuno)

Japan&#39;s Crown Prince Naruhito, heir to the world&#39;s oldest monarchy, may be best known for his persistent courtship of Crown Princess Masako and the couple&#39;s lengthy wait for their first child.

On Saturday, Masako gave birth to a girl after more than eight years of marriage.

Naruhito appeared as proud as any new father, though the birth will intensify debate over whether to change the law to allow a female to inherit the world&#39;s oldest hereditary monarchy.

Naruhito, the 41-year-old eldest son of Emperor Akihito and Empress Michiko, became crown prince in January 1989 when his grandfather Hirohito died and Akihito acceded to the throne.

Three years earlier, Naruhito was smitten with Masako with the dynamic career diplomat, whom he met at a concert for visiting Spanish royalty at the imperial palace.

But it took all his efforts to bring off the match, which faced objections from courtiers in the stuffy Imperial Household Agency and reluctance on the part of Masako herself.

The diminutive prince, standing 1.63 metres (5 ft 3 inches) tall, once said that neither height, family connections nor academic background would affect his choice of a bride - whom he hoped to find by the time he was 30.

But it was not until he turned 32 that Naruhito won Masako&#39;s consent after an eight-month courtship.

Phoning her night after night, he finally won her heart by promising to protect her from the worst demands of her new life behind Japan&#39;s "Chrysanthemum Curtain".

The demands are not slight.

Naurhito&#39;s mother, the Empress Michiko, is believed to have come to the brink of a nervous breakdown during the early years of her marriage due to bullying by court officials.

A broad smile never left Naruhito&#39;s face during the June 1993 nuptials.

WAIT FOR AN HEIR

The crown prince handled early questions about a baby with humour. "The stork needs peace and quiet in which to work," he quipped at one news conference several years into his marriage.

But as time time passed, his responses grew terse.

"I fully recognise the degree to which people are interested in this, and the importance of the matter," he replied at a news conference on his 39th birthday.

Masako miscarried in 1999 after a brief pregnancy that set off a media frenzy, and at a news conference on his 40th birthday the next year, Naruhito made rare attack on the media.

Calling the furore "truly deplorable", Naruhito said: "I hope that in future such issues will be handled in a more prudent and considerate way."

MODERN PRINCE

In many ways a symbol of modern Japan, Naruhito -- known as Prince Hiro during his early years -- was the first prospective emperor to live with his parents from birth. His father and grandfather, Emperor Hirohito, were both raised by courtiers.

He studied at the elite Gakushuin school in Tokyo, where he excelled in social studies and Japanese language but did poorly in maths. He continued his studies at Gakushuin University, where he specialised in the history of transport in the Middle Ages.

In 1983, he became the first heir to the throne to study abroad, reading mediaeval European transport and economics at Oxford University&#39;s Merton College. He took up his official duties after returning home in 1985.

The crown prince&#39;s interests include mountain climbing, tennis and skiing. He also plays viola, sometimes accompanied by the Crown Princess on the flute.

The illness which Masako is suffering is quite a unpleasant one.
It&#39;s extremely painful. When you touch them (they are like bubbles), it&#39;s hot and extremely painful. This rashes are mainly developed from over-tiring. Poor Masako.